This invention relates to a code image recorder which transforms input data concerning a piece of sound, image or text information into code image data conforming to a predetermined physical format, and which then prints/records the code image data as an optically readable code image on a predetermined recording medium.
U.S. Pat. Nos. 5,896,403 and 5,866,895 describe respective code image readers which optically read a dot code to be printed/recorded at a high density as an optically readable code image representing a piece of sound, image or text information, and which then reproduces the original piece of information in the form of sound, image or text.
FIG. 1 shows the physical format of a dot code 10 disclosed by the above cited U.S. Patents.
A plurality of blocks 12 are arranged two-dimensionally side by side and each of the blocks 12 comprises a data dot pattern region 14, markers 16, pattern dots 18 and a block address pattern 20. The data dot pattern region 14 is a region where the data of the block obtained by dividing the original data concerning a piece of information in the form of sound, image or text is arranged as a dot image formed by white dots or black dots representing respective bit values of xe2x80x9c0sxe2x80x9d or xe2x80x9c1sxe2x80x9d and arranged according to a predetermined format. The markers 16 operate as so many reference indexes to be used for locating the reference positions when reading the dots within the data dot pattern region 14. The markers 16 are located at the four corners of the block. Each marker 16 is formed of a predetermined number of black dots arranged sequentially. The pattern dots 18 are arranged in a line, which extends between two adjacent ones of the markers 16. The pattern dots 18, some of which are black and the others of which are white, are arranged in a prescribed pattern. The block address pattern 20 is arranged between a pair of markers of the block so that it may be identified when reading a plurality of different blocks. The data represented by the block address pattern 20 include the address data of the block and an error detection code or an error correction code.
FIG. 2 is a schematic block diagram of a code image reader 22 adapted to optically read such a dot code 10.
The code image reader 22 comprises at least an imaging section 24, an image memory 26, a binarization processing section 28, a binarized image memory 30, a restoring section 32, a demodulator section 34 and a reproducing section 36.
The imaging section 24 includes an illumination section typically comprising an LED for illuminating the dot code 10, an optical system for focussing the light reflected by the dot code 10 and a solid imaging device such as CCD for imaging the focussed image produced by the optical system. The image memory 26 stores the digital imaging signal obtained by digitizing the imaging signal output from the imaging section 24. The binarization processing section 28 reads out the digital imaging signal stored in the image memory 26 and binarizes the signal by means of a predetermined binarization threshold value. The binarized image memory 30 stores the binarized image data produced from the binarization processing section 28. The restoring section 32 reads out the binarized image data stored in the binarized image memory 30, detects the dots of the dot code and assigns xe2x80x9c0xe2x80x9d or xe2x80x9c1xe2x80x9d to each detected dot before it outputs the modulated data without processing it. The demodulator section 34 demodulates the modulated data output from the restoring section 32. The reproducing section 36 reproduces the data concerning the information in the form of sound, image or text demodulated by the demodulator section 34.
The code image reader 22 can read out the dot code if the dot code is sized to exceed the imaging field of the imaging section 24 as the imaging section 24 divides the dot code into frames and moves above the code image to sequentially pick up the dot code on a frame by frame basis. In other words, if the dot code 10 cannot be imaged by a single shot and can only be covered by a multiple of shots, it can be recognized and restored from the data of the blocks 12 once the addresses of the blocks 12 are read out and recognized. Thus, a large amount of information can be densely stored on a sheet of paper or some other medium to such an extent that conventional one-dimensional or two-dimensional bar codes can never achieve. Then, a long speech can be transmitted by way of a sheet of paper or some other medium to provide such a code image recorder with a wide variety of potential applications.
When reading out the binarized image data from the binarization image memory 30 and detecting each dot contained therein, the restoring section 32 firstly detects the markers 16 out of the binarized image data. Then, it searches the pattern dots 18 on the basis of the detected markers 16 and the information on the physical format and computationally determines reference positions for the operation of reading the block by minimizing the error function determined from the ideal center position of each of the pattern dots 18 contained in the above information on the physical format and the actually located center position thereof. Then, the restoring section 32 detects the center pixel of each of the dots to be read out within the data dot pattern region 14 and determines if the detected dot is a white dot or a black dot, to which a value of xe2x80x9c0xe2x80x9d of xe2x80x9c1xe2x80x9d is assigned so that a modulated data will be output for it.
Thus, if the highly densely printed/recorded code image shows a rather poor printing quality, the dot code will be read out correctly and a high quality reading operation will be guaranteed.
The demodulator section 34 restores the unmodulated original data as the original data concerning the information in the form of sound, image or text input to be recorded is modulated when a code image data is prepared therefrom. The modulation is carried out to facilitate the operation of the restoring section 32 of detecting the markers 16 to begin with. As a result of the operation of modulating the input data concerning the information in the form of sound, image or text, the number of consecutive black dots within the data dot pattern region 14 is made smaller than the number of consecutive black dots of the markers 16 in order to visually discriminate the dots within the data dot pattern region 14 and the markers 16.
For example, if the largest diametrical length of the marker 16 shown in FIG. 3 is equal to the length of five consecutively arranged black dots printed/recorded in the data dot pattern region 14, the input data concerning the information in the form of sound, image or text is modulated in such a way that the number of any consecutively arranged black dots contained therein may become less than five after the modulation.
Meanwhile, generally two methods are conceivable for printing/recording a highly dense dot code 10 on a sheet of paper. One is a method of printing the code to produce a large number of copies by means of a printing plate made by an image setter. The other is a method of using a printing technique such as thermal transfer or laser printing. The above cited U.S. Pat. No. 5,896,403 proposes the use of the above two methods for densely printing/recording a dot code 10 on a sheet of paper.
However, it has been found as a result of recent researches that the latter method of printing dot codes is accompanied by the following disadvantage.
When printing a dot code 10 by a thermal transfer type printing means, the control signal for heating each of the thermal recording elements of the thermal recording head is devised to make the area of a printed dot smaller than the recording area of the thermal recording element used for printing the dot.
Then, since each marker 16 is formed by arranging a plurality of dots side by side as minimal printing/recording units, gaps are inevitably produced within the printed/recorded marker 16 as a result of using such a technique of reducing the area to consequently produce a marker containing white spots therein. Then, it can be no longer possible to discriminate such a marker from a dot contained in the data dot pattern region 14 to give rise to a serious problem of operation errors on the part of the code image reader.
Since the copying means is provided by necessity with a mechanism for mechanically driving the recording medium such as a sheet of paper and the thermal recording head and the variances in the accuracy of operation of feeding paper of the mechanism is believed to promote the production of markers containing white spots therein.
Thus, for code images of the type under consideration including dot codes, reference indexes such as markers 10 that operate as references for reading dot codes take a vital role in the data reading operation and hence have to be printed/recorded highly accurately and reliably. Then, reference indexes can become visually defective when code images are printed/recorded by the printing means.
Reference indexes may be printed/recorded without white spots by uniformly controlling the timing of feeding paper for an entire code image or that of printing/recording an entire code image relative to the recording device by means of the technique disclosed in Japanese Patent Disclosure (KOKAI) No. 56-86775 or No. 10-3509 so that the printed dots may overlap each other. However, with either of the disclosed techniques, not only the dots of the reference indexes but also those in the data dot pattern region 14 can be printed/recorded in an overlapping manner. Then, some of the dots that are printed/recorded with a reduced size can become large as a result of overlapping to make it possible to print/record a code images highly densely.
In view of the above circumstances, it is therefore the object of the present invention to provide a code image recorder adapted to accurately and reliably print/record reference indexes that operate as references for reading out an optically readable code image without adversely affecting the subsequent operation of reading the code image so that the code image may be printed/recorded highly densely.
According to an aspect of the present invention, there is provided a code image recorder adapted to modulate input data concerning a piece of sound, image or text information, and to form an image therefrom according to values of obtained modulated data so as to print the information on a predetermined recording medium as an optically readable code image by rendering a number of consecutive predetermined identical data values in the modulated data smaller than a number of consecutive predetermined identical data values contained in at least one optically readable reference index operating as a reference for reading the code image to make the modulated data discriminable from the optically readable reference index, the code image recorder comprising code image data generating means for receiving the modulated data and data constituting the reference index as input, and for generating code image data as a bit map corresponding to a physical format of the code image; and printing means for receiving the code image data generated by the code image data generating means, and for optically readably printing a corresponding code image on a predetermined recording medium, wherein an image corresponding to the consecutive predetermined identical data values is solidly printed only for the reference index in the code image.
Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter.